How to download attachments for issue via jira-rest-java-client-core?

Question

I need to download all attachments for specified issue in jira. 
This code downloads file, but it's corrupted. 
Can anyone help, how to correctly work with attachments?

import com.atlassian.jira.rest.client.api.JiraRestClient
import com.atlassian.jira.rest.client.internal.async.AsynchronousJiraRestClientFactory
import java.io.FileOutputStream

import java.net.URI
import java.nio.channels.Channels
import java.io.BufferedInputStream
import java.io.IOException
import java.net.URL

@Throws(IOException::class)
private fun downloadUsingStream(urlStr: String, file: String) {
val url = URL(urlStr)
val bis = BufferedInputStream(url.openStream())
val fis = FileOutputStream(file)
val buffer = ByteArray(1024)
var count = 0

while (bis.read(buffer, 0, 1024) != -1) {
        fis.write(buffer, 0, buffer.size)
    }
    fis.close()
    bis.close()
}

fun main(args: Array<String>) {
val jiraURI = URI("http://jira/")

val factory = AsynchronousJiraRestClientFactory()

val client: JiraRestClient = factory.createWithBasicHttpAuthentication(jiraURI,"login","password")
val issueClient = client.issueClient

client.use {
            issueClient.getIssue("attachment").claim().attachments.forEach {attachment->

val website = attachment.contentUri.toURL()
downloadUsingStream(website.toString(),attachment.filename)

}
    }

}

Chirag Taraviya · Answer

@蒋雨辰Can you please suggest anything in php for this issue? Or just basic steps with jira url.

蒋雨辰 · Answer

Thank god, finally I find a solution in Java.

JiraRestClient client = factory.createWithBasicHttpAuthentication(jiraURI,"login","password")

//cast  JiraRestClient to AsynchronousIssueRestClient
AsynchronousIssueRestClient issueClient=(AsynchronousIssueRestClient) client.getIssueClient();

URL url=new URL("your attachment url");
Promise<InputStream> attachment=asynchronousIssueRestClient.getAttachment(url);
InputStream inputStream=attachment.get();

//then you can do whatever you want with that inputStream